Abrasive disk



- ug. 2, '1938. H. o suDHAuss ABRAsIvE nIsx Filed sept. 26. 193sPatented Aug. 2,. 1938 PATENT oFI-ICE .ABRASIVE DISK Herman 0.Sundhauss, Chicago, lll., assigner to JoseplrL. Eisendrath, Jr.,Chicago, Ill.

Application September 26, 1936, Serial No. 102,736

2 Claims.

coating or facing of grit particles on its outer face, v

and has a hole in the central portion for receivlng the centering hub ofthe head and also has lo a pair of diametrically opposite slots whichradiate from the hole and are adapted to receive and interlock with thelocking wings and form a driving connection between the head and backingpiece.

Heretofore it has been customary in the fabrication of a disk of thistype to make the wing receiving slots of uniform width from end to end.In practice it. has been found that an abrasive disk having slots ofthis character is defective or objectionable for two reasons. In the rstplace it is extremely diiiicult to mount the disk due to the fact that`the portions of the backing piece which dene the slots are soinflexible or stiff that they cannot readily be ilexed or dis- `tortedin order to permit of entry of the'locking wings of the head into theslots. Secondly, rupture or tearing of the backing piece is likely tooccur at the outer ends of the slots in connection with a disk mountingoperation due to the of th' diametrically opposite wing receiving sl'otscomparatively large. .circular holes which serve to free or disconnectthe ends ofthe slot defining portions of the backing piece from theportions adjacent to the ends of the slots with the result that suchslot deiining portions can readily be flexed or distorted in connectionwith a disk mounting operation and when: flexed or distortedsuiiiciently to permit of entry of the wings into the slots do rnotplace tearing strain uponthe portions of the backing piece adjacent tothe ends of the slots. Y

Another 'object of the invention is to provide an abrasive disk of theaforementioned type in which the diametrically opposite wing receivingyslots 5 with the comparatively large holes at the outer ends thereofare arranged or positioned so that they extend at substantially rightangles to the grain of the backing piece. I

A further object of the invention is to provide 1o an abrasive stripwhich is generally of new and improvedconstruction.

Other objects of theinvention and the variousj advantages andcharacteristics of the present abrasive disk will be apparent from aconsidera- 15 tion ofthe following detailed description.

The invention consists in the severeal novel features which arehereinafter set forth and are` more particularly dened by claims at theconclu'sion hereof.

In the drawing which accompanies and forms a part of this specificationor disclosure and in which like numerals of reference denotecorresponding'parts throughout the several views:

Figure 1 is a bottom view of an abrasive .disk

embodying the invention;

Figure 2 is a plan view 'showing the disk mounted on a rotary head;

Figure 3 is a sectional view taken on the line 3 3 of Figure 2 andshowing in detail the manner in' which the wings on the rotary headinterlock with the diametrically opposite slots in the disk in order toform a driving connection between the head and the disk;

0f Figure 2;

Figure 5 is a perspective showing the manner in. which the holes at theouter ends of the wing receiving slots free the outer ends of the slotdefining portionsof the backing piece of the disk 40 so that suchportions may be readily flexed in connection with mounting of the diskand when flexed suiciently to permit of entry of the wings of the rotaryhead do not impart tearing strain to the portions of the disk at theends of the slots; 45 and Figure 6 is an enlarged section showing theextent to which it is necessary to flex or distort the slot deningportions of the backing piece in order to permit the wings to passtherebetween 50 in connection withmounting of the disk on the head.

The abrasive disk which forms the subject matter of the invention isessentially a surfacing element. It is adapted for use with a rotaryhead Figure 4 'isa sectional view on the line 4 4 35 H and consists of acircular backing piece 'l with a coating 8 of grit particles on theouter or top face thereof. The rotary head H is shown. in the drawing asbeing of conventional design and has on the front end thereof acentering hub h and a pair of wings hil. It is adapted to be moved overthe work as well understood in the art and is driven by an electricmotor (not shown) through the medium of a flexible shaft h. The latterextends through a sheath h3 and embodies a driving element h4 which fitswithin av socket h5 in the central portion of the rotary head H and isdrivably connected to the head by means of a 'screw thread connection h.The hub h is formed as an integral part of the head. It is centrallypositioned with respect to the head and is circular, as shown in Figure3., The wings h1 of the head are positioned on opposite sides of the hubh, and project in opposite directions. The base portions of the wingsextend radially outward from the hub and are' anchored inv any suitablemanner on the head. The outer portions of the wings h1' are spaced-asmall distance from the outer face of the head H and extend in acircumferential manner and in substantially parallel relation with theouter face of the head. A ring h" of rubber or like material is fixed tothe front face of the head and surrounds the wings h1. It -forms part ofthe head and serves as a backing member for the disk.

The backing piece 1 is adapted when the disk is mounted on the head H,as hereinafter described, to fit against the front faces of the head Hand the ring h". It is formed of processed o r chemically treated paperand has the coating I of grit particles'secured to its front face bymeans of a film 9 of cement. As shown in the drawing the backing plateis slightly larger in diameter than the ring h" of the rotary head H.The backing piece although comparatively thin is comparatively stii! dueto its processing or chemical treatment and the fact that the'coating 8of grit particles is substantially rigid in characer due to embedment ofthe particles yin gli scementitious material which forms the The diskhas a holel Il in the center thereof' mounted on the head H. The slotsIl radiate from the hub-receiving hole 'I0 in the center of the disk andare adapted to receive the wings h1 of the rotary head H and form adriving connec.

tion between the head and the disk. They intersect the hole Il and arearranged so that they extend transversely of the grain of the/backingpiece 1. In connection with the mounting of the disk on the head H it isnecessary to flex or distort the slot defining portions of the disk asumcient distance to permit of entry of the wings h1 into the slots. Theholes i2 at the outer ends of the slots serve to free the outer ends ofthe slot dening portions of the disk so that such portions can readilybe flexed or distorted. Preferably the holes are formed so that thediamevends of the slots that they may be flexed or distortedsufiiciently to permit of ready entry of thel wings hl into the slotswithout imparting tear ing strain or causing. rupture of the diskoutwardly from the outer ends of the slots. The holes l2 constitute theouter ends of the slots and, as shown in Figure 2, receive the outerportions of the base parts of the wings h1.

In applying the disk to the head H the portions the sides of the otherslot i iA are deflected one upwards and the other downwards and the diskis manipulated so as to bring the other wing hl therebetween. Aftermanipulating the disk in this manner it is turned or rotated relativelyto thehead so as to bring the centering hub h and the base parts of thewings h1 into seated relation with the hole I0 and the slots Ilrespectively. By reason of the fact that the slots Il extend crosswiseof and are at substantially right angles to the grain. of the backingpiece 1 and the holes I2 are of the diameter hereinbefore specified,there is little if. any likelihood ofthe portions of the disk which aredisposed outwardly of the holes i2 being ruptured or torn during flexureof the slot defining portions of the disk in connection with mounting ofthe disk on the rotary head I. l

The herein described disk due to thefact that it includes at the outerends of the slots Il the holes I2 whereby the outer ends of the slotdefining portions of the disk are freed or severed from the portions ofthe disk at the ends of the slots, may be readily mounted and isextremely durable. lin orderl to reduce the cost of manufacture. thehole il, the slots Il, and the holes I2 are formed in the centralportion of the disk by'a single cutting operation.

`'111e invention is not to be understood as restricted to the detailsset forth, since these may be modified within the scope of the appendedclaims, without departing from the spirit and scope of the invention.

Having' thus described the invention, whatv 1 claim as new and desire tosecure by Letters Patent is:

1. As a new article of manufacture, an abrasive disk in the form of acomparatively stiff backing piece with a coating of grit particles onone face thereof and adapted to be mounted on a rotary head having acentering hub and a piurality of oppositely facing wings positionedadjacent to the sides of the hub and extending outwardly andsubstantially parallel to thel front face of the head, said disk havinga hole in the central portion thereof for receivingthe 'centering hub ofthe head and a plurality of. slots extending outwardly from the hole andadapted to receive and interlock with the locking wings, and also havingcomparatively large holes at the outer ends of the slots serving to freeor sever the outer Vends of the slot forming portions of the disk and topermit such portions to be flexed or distorted out of the plane of thedisk and without causing the disk to rupture or crack at the outer endsof the slots in connection with insertion of the wings into the slotsduring disk mounting.

2. As a new article of manufacture, an abrasive disk in theform of abacking piece of comparatively sti paper with a coating of gritparticles on one face thereof and adapted to be mounted on a rotaryheadfhaving a centering hub and a pair of oppositely facing lockingwings radiating from opposite sides of the hub and extending outwardlyand substantially parallelfwith the front face of the head, said diskhaving a hole in the central .portion thereof for receiving thecentering hub of the head and a pair of diametrically opposite slotsextending radially from the hole and transversely of the grain of thebacking piece and adapted to receive and interlock with -the lockingwings, and also having comparatively large holes at the outer ends ofthe slots serving to free or sever the outer ends of theslotvformingportions of. the disk and to permit such portions `to be exed ordistorted out of the piane of the disk and without causing the disk torupture or crack at the outer ends of the slots in'connection withinsertion of the wings into theslots during disk mounting.

HERMAN 0. SUNDHAUSS.

